World War II began with the German invasion of Poland on 1 September 1939. The subsequent 36-day campaign triggered a global war that lasted six years. The Poland Campaign was soon overshadowed by the campaigns and battles that followed. As a result, it is best remembered today by series of myths and legends, almost all of them untrue. Contrary to the most popularly cherished beliefs about World War II, Polish horse cavalry units never mounted suicidal charges against German panzers; the Polish air force was not destroyed on the ground on the first day of the war; and the Polish army was far from being a pushover for the German army.

Under the command of Marshal Edward Rydz-Smigly, the Polish army in the summer of 1939 had roughly 500,000 men, organized into 30 regular and 9 reserve infantry divisions, 11 cavalry brigades, and 2 mechanized brigades. The Polish army had 887 tanks, less than a third of the almost 2,500 tanks fielded by the Germans. When it became obvious they would be attacked by Germany, the Poles opted for a forward defense, which was designed to withdraw slowly to the east to buy more time for mobilization. Plan zachod (West), issued on 23 March 1939, correctly assumed that the German main attack would come from Silesia in the direction of Warsaw, with supporting attacks from German Pomerania and East Prussia. The Poles therefore positioned four armies along Poland's western border. In north-central Poland, one army was positioned to defend Warsaw from a German thrust south from East Prussia. After the Germans moved into Slovakia, the Poles also established a weak army in the south to defend the passes through the Carpathian Mountains.

The concept of Plan zachod was based on a fighting withdrawal, with Armies Pomorze, Poznan, and Lodz all falling back to the west, while pivoting on the strong Army Krakow, the southern anchor of the Polish line. Many military historians have been highly critical of the Polish plan, positing that Poland's armies were deployed too far forward and spread far too thin. But the Polish army by itself could have never beaten the Germans, regardless of its strategic plan. The Polish-German border was 1,250 miles long, and the German extension into Bohemia and Moravia and Slovakia added another 500 miles. Plan zachod was based on the assumption of a strong attack by Britain and France against Germany in the west. Unfortunately for the Poles, that promised attack never came.

In August 1939, the Wehrmacht had 51 active divisions, 51 reserve divisions, and 1 active cavalry brigade. All the reserve divisions were infantry units, and the active force included 6 panzer and 4 motorized divisions. The average panzer division had 310 tanks, most of which were the lightly armed PzKpfw-I and PzKpfw-II models. The Germans had a total of about 500 of the heavier PzKpfw-III and PzKpfw-IV tanks. They also made use of PzKpfw 35(t) and PzKpfw 38(t) tanks, redesignated Czech machines acquired in the March 1939 takeover of Bohemia and Moravia. The Wehrmacht's active strength was roughly 730,000 men, and its reserve strength was about 1.1 million men.

On 3 April 1939, Adolf Hitler's headquarters responded to British Prime Minister Neville Chamberlain's declaration of support for Poland by issuing Fall weiss (Case white), the plan for the invasion. The success of Fall weiss hinged on a calculated political risk that made most of Hitler's generals nervous. The Germans had to secure a quick victory in Poland in order to shift their forces rapidly back to the west to fend off any attack from the French and British. The Wehrmacht of 1939 was neither large nor strong enough to mount simultaneously a massive attack in the east and a strong defense in the west. Thus, the attack in the east could only be strengthened at the risk of weakening the defense in the west. Willing to gamble that the French and British would not act in time to save Poland, Hitler took that risk. Fall weiss then called for Germany's border with France to be guarded by the relatively weak Army Group C, which consisted of 21 active and 14 reserve divisions.

A total of 52 divisions, including all of the panzer and motorized divisions, were allocated for the attack on Poland. They were organized into Army Group North and Army Group South under Colonel Generals Fedor von Bock and Gerd von Rundstedt, respectively. The original plan did not include military operations east of the Vistula, on the assumption that Soviet forces would move rapidly into that area. The campaign would end with the Tenth Army linking up with Army Group North at Warsaw, sealing off the Polish units in western Poland and preventing them from escaping east to the Narew–Vistula–San River line.

Beginning in July, 386,000 army and 55,000 Luftwaffe reservists were called to active duty under the guise of training maneuvers. By the end of August, Army Group North had a strength of 630,000 men, and Army Group South had 886,000. Hitler initially set 26 August as Y-Day, the start of the attack. But then Hitler himself blinked when Britain and France on 24 August responded to the German-Soviet Non-aggression Pact of the day before by giving Poland written guarantees of military support and when Benito Mussolini backed off bringing Italy into the war on Germany's side. Late on 25 August, Hitler canceled the attack orders, but several small German units still crossed the frontier and clashed with Polish border guards before they could be recalled.

After a few more days of diplomatic cat-and-mouse games, Hitler on 31 August signed "Führer Directive No. 1 for the Conduct of the War." On 30 August, Rydz-Smigly decided to order a general mobilization. That move brought an immediate and sharp reaction from Poland's erstwhile allies, Britain and France, which were afraid of provoking Germany and which remembered only too well the spiral of mobilizations that triggered World War I. Within three hours, the French government had pressured Rydz-Smigly into revoking the mobilization order.

With the German forces in position and ready to move, Hitler needed only an incident of provocation to provide him with a fig leaf of respectability. Leaving nothing to chance, the German Sicherheitsdienst (SD), dressed in Polish uniforms, "raided" the German Silesian town of Gleiwitz on the night of 31 August. They seized the local radio station and played a prerecorded anti-German message in Polish. After firing off a few rounds for effect, the SD unit withdrew, leaving behind several "Polish casualties" as evidence. The bodies were actually prisoners from the Sachsenhausen concentration camp dressed in Polish uniforms and murdered specially for Hitler's little charade.

According to the Fall weiss plans, the invasion was to commence at 4:45 a.m. on 1 September. The first shots of World War II were fired 15 minutes early, however, when three dive-bombers of the 3/1st Stuka Geschwader hit a Poznan air base, which turned out to be deserted. The Luftwaffe immediately followed through with attacks on Polish airfields and rail centers. For the most part, the attacks on the Polish airfields were failures. Anticipating the strikes against the bases, the Polish air force on 31 August dispersed its frontline aircraft to secret secondary bases to avoid having them caught and destroyed on the ground.

The Luftwaffe dwarfed the Polish air force, which had only 392 first-line combat aircraft. The Luftwaffe in March 1939 had a strength of 4,303 aircraft, including 1,180 bombers, 336 dive-bombers, and 1,179 fighters. In support of the German invasion, Army Group North was allocated Luftflotte 1 under General Albert Kesselring; Army Group South was supported by General Alexander Löhr's Luftflotte 4. The combined force totaled 36 groups and included all of Germany's dive-bombers, 70 percent of its bombers, and 50 percent of its fighters.

Vastly outnumbered and technically outclassed, the Polish pilots put up a stiff resistance. The law of numbers, however, dictated that the Polish air force would play only a marginal role in the overall outcome of the campaign. By 6 September, Polish fighter units were down to 50 percent of their original strength. A few days later, the surviving fighters began withdrawing toward Romania with the rest of the Polish army.

In the end, the Poles lost almost 300 of their combat aircraft, and they evacuated 98 to Romania. But the Germans suffered heavy losses as well, with 285 aircraft destroyed and another 279 severely damaged. Despite the great technological disparity in aircraft, Polish fighter pilots scored at least 121 confirmed air-to-air kills for the campaign. German records indicate that the true number may have been closer to 160.

The Poles had no illusions about their strategic situation. On 30 August, Vice Admiral Jozef Unrug, commander of the Polish navy, initiated Operation peking, ordering Poland's three modern destroyers to leave immediately for British ports. At 4:43 a.m. on 1 September, the old German battleship Schleswig-Holstein opened fire on the Polish military supply base on Westerplatte island in Danzig harbor.

The ground war started within minutes of the Schlewsig-Holstein opening fire. In the north, visibility was limited by heavy ground fog as von Bock's units jumped off. The Third Army, under General Georg von Küchler, attacked south toward Warsaw, and General Günther von Kluge's Fourth Army sliced into the Polish Corridor, which divided East Prussia from the rest of Germany. The Fourth Army's objective was to clear a path for the one panzer and two motorized divisions of General Heinz Guderian's XIX Corps to drive a pincer arm southwest toward Warsaw.

The weather in the south, meanwhile, was clear as Army Group South crossed into Poland. General Johannes Blaskowitz's Eighth Army drove toward the Polish industrial city of Lodz. In von Rundstedt's center, his Tenth Army, under General Walther von Reichenau, struck from Oppeln toward Czestochowa, Piotrkow, and Tomaszow to encircle Warsaw from the south. The Fourteenth Army, under Colonel General Wilhelm List, attacked from German Silesia and Slovakia to cut off Krakow.

By 4 September, the Germans had managed to drive a deep wedge between Army Lodz and Army Krakow. On 5 September, the first major clash between German and Polish tanks occurred at Piotrkow. At the end of the day, the Germans penetrated Polish defenses and secured the key road links to Warsaw. The breakthrough at Piotrkow marked the end of the first phase of the Poland Campaign. By the evening of 5 September, the Polish armies were retreating all along the line. With his thin defensive shell cracked, no reserves to commit, and much of his army still mobilizing, Rydz-Smigly believed he had no alternative but to order a withdrawal to the line of the Vistula. Simultaneously, German field commanders such as Guderian were smelling victory and pushing the German High Command to authorize operations beyond the Vistula.

Warsaw was now directly threatened. On 7 September, Rydz-Smigly compounded the Polish command-and-control problems by ordering the withdrawal of the High Command eastward to Brzesc (Brest). The Polish command-and-control infrastructure was primitive to begin with, but the move from Warsaw to Brzesc virtually guaranteed that the Polish High Command would no longer play any significant role in managing the campaign. In the north, meanwhile, the Fourth Army pushed Army Pomorze out of the Polish Corridor, bypassed Army Poznan, and was approaching Warsaw. On 8 September, the 4th Panzer Division attempted to take the Polish capital by storm, but it was driven back and lost 60 armored vehicles after heavy street fighting.

In their rush to reach Warsaw, the Germans lost track of General Tadeusz Kutrzeba's bypassed Army Poznan. They assumed that it had been pushed back as well and was now incorporated into the Warsaw garrison. Kutrzeba's force, in fact, was entrenched behind a bend in the Bzura River about 30 miles west of Warsaw. Locally, Kutrzeba held a 3:1 superiority in infantry, and he decided to attack. The Bzura River Offensive was the only major Polish counterattack of the campaign. On 9 September, the Poles caught the German 24th and 30th Infantry Divisions by surprise, capturing more than 1,500 prisoners from the 30th Division alone. But the Germans, with their far greater mobility and firepower, were able to shift other forces rapidly to contain this Polish offensive. Army Poznan finally surrendered on 21 September, with the Germans capturing more than 100,000 Poles.

With the Buzra Offensive under control, the Germans were then able to turn their attention back to Warsaw to conduct a set-piece siege. On 15 September, the German Third Army forced its way into Warsaw's Praga district on the east side of the Vistula. By 23 September, Warsaw's food and water were running out and the city was completely ringed by 13 German divisions and more than 1,000 guns. On 25 September, a day the Poles still call "Black Monday," Hitler personally ordered an armada of 420 German bombers to savage the capital with repeated sorties. Warsaw finally surrendered on 27 September, after suffering some 2,000 military and 40,000 civilian dead.

It quickly became obvious to Rydz-Smigly that his order to withdraw to the rivers had come too late. With their vastly superior mobility, the Germans were able to reach the river lines before the Poles could man them. Given approval by the High Command, German field commanders now advanced their forces east of the Vistula. On 9 September, the Fourth Army initiated a drive toward Brzesc that was spearheaded by Guderian's XIX Corps. Two days later, Rydz-Smigly ordered the surviving Polish units to withdraw toward the southeast, to the so-called "Romanian Bridgehead."

Plan zachod had been based on holding until the French and British could attack Germany from the west. The Poles were promised that attack no later than 16 September. It did not occur. On 17 September, Soviet leader Josef Stalin drove the final nail into the Polish coffin by invading Poland from the east. Hiding behind the excuse of occupying eastern Poland "to protect its fraternal Byelorussian and Ukrainian populations," the Soviets marched in with two fronts (army groups). The Byelorussian Front, under General M. P. Kovalev, and the Ukranian Front, under General Semen Timoshenko, had a combined strength of 24 infantry divisions, 15 cavalry divisions, and 2 tank corps.

The Soviet invasion caused immediate problems for the German field commanders, who already were operating well to the east of the demarcation line agreed to in the German-Soviet Non-aggression Pact. On 20 September, Hitler ordered a withdrawal to the designated line, with movement to start the next day. The Soviets reached the Bug River on 23 September. On the diplomatic level, meanwhile, the Soviet government initiated negotiations to shift the line to the east in exchange for Lithuania. The Germans agreed, and on 1 October the new demarcation line was established along the general line of the Bug River. The result was to extend the German zone to the east by as much as 100 miles in some places.

Poland suffered staggering losses in the campaign, amounting to 66,300 killed, 133,700 wounded, 587,000 taken prisoner by the Germans, and another 200,000 taken prisoner by the Soviets. Polish civilian deaths were close to 100,000. Virtually all of Poland's military hardware was destroyed or captured, with the exception of the handful of obsolete fighters that escaped to Romania.

Despite the claims of German Minister of Propaganda Josef Goebbels, the Germans paid a high price for such a short campaign. The Wehrmacht suffered 16,000 dead and 32,000 wounded. It lost 217 tanks totally destroyed and another 457 so heavily damaged that most never returned to service. Thus, the Germans lost one-quarter of the tanks as well as one-fifth of the combat aircraft they committed to the campaign. On top of that, they expended eight months' worth of fuel, ammunition, and repair parts in an operation that lasted little more than one month.

The performance of the Polish military can perhaps be put into proper perspective by comparing it with that of the western Allies in the spring of 1940. Only partly mobilized, vastly outnumbered, with obsolete weapons, and attacked from all sides, the Poles held out for 36 days and inflicted heavy losses on the Germans. The British, French, Belgians, and Dutch had almost nine months to mobilize and prepare. When war did come in the west, the Allies had near parity in ground and air forces, actual superiority in tanks, and outright supremacy at sea. Yet, in a 39-day campaign, they inflicted fewer losses on the Germans than had the Poles.

The Anglo-French failure to deliver their promised attack on Germany in September 1939 remains one of the great "what-ifs" of the twentieth century. Strong Allied intervention in the west might not have saved Poland in the end. On the other hand, it certainly would have forced Germany into a two-front war two years earlier than the German invasion of the Soviet Union. The German war machine of 1939 was nowhere near as large and strong as it would be by June 1941. In September 1939, French and British forces were capable of throwing 98 divisions and some 3,500 combat aircraft against Army Group C's 35 infantry divisions supported by about 1,000 aircraft. Behind them lay the vulnerable industrial base of the Rhineland. But in the end, the French made only a feeble effort into the Saarland; the British record was worse and largely confined to debate over the legality of using the Royal Air Force to bomb private property in Germany.

World War II started over Polish independence. Yet in one of the greatest ironies of history, that very independence was bargained away in the deals between the victorious powers at the war's end. The Yalta and Potsdam agreements left Poland on the wrong side of the Iron Curtain, and despite a deep historical antipathy toward the Russians, the Polish people had to endure more than four decades of Soviet domination during the long winter of the Cold War.

David T. Zabecki

Further Reading
Dziewanowski, Marian K. War at Any Price: World War II in Europe, 1939–1945. Englewood Cliffs, NJ: Prentice-Hall, 1991.; Hollingworth, Clare. The Three Weeks War in Poland. London: Duckworth, 1940.; Kennedy, Robert M. The Campaign in Poland (1939). U.S. Department of the Army Pamphlet 20–255, April 1956.; Rossino, Alexander B. Hitler Strikes Poland: Blitzkrieg, Ideology, and Atrocity. Lawrence: University Press of Kansas, 2003.; Zagola, Steven, and Victor Madej. The Polish Campaign, 1939. New York: Hippocrene Books, 1985.